Lifters are an integral part of an automobile valvetrain, along with the valves themselves, the camshaft and rocker arms. As the camshaft rotates, the camshaft lobes raise and lower the pushrods, which in turn, cause the rocker arm to depress and release the valves, allowing fuel to enter the combustion chamber and exhaust to exit. The General Motors 3100 is a 3.1-liter, V-6 engine produced during the 1990s, and was featured on numerous GM automobile models. Valve lifters sometimes stick, or bend in extreme situations. Sticky valves can be fixed; bent valves require replacement.
Raise and secure the hood, and check the oil by pulling out the dipstick and reading at the cold setting. Add oil if the engine is low. Recheck the oil to ensure a proper oil level. Start the engine and allow it to heat up for fifteen minutes, allowing it to reach operating temperature.
Listen for valve noise emanating from the valve covers, located on either side of the carburetor, on the top of the 3100 engine. Stuck lifters produce a loud clacking sound. Remove each valve cover while the engine is running. Use a socket wrench and socket to remove the bolts surrounding each valve cover.
Inspect the valve lifters while the engine is operating. Look at each one, checking if the lifter is operating, and if the rocker arm is depressing the valves. The rocker arms are in the center of the cylinder head; the valves are covered with a spring.
Use penetrating oil, such as Kroil, Marvel Mystery Oil or PB Blaster. Penetrating oil is an oil treatment additive the helps break up gunk and oil deposits. Pour a sufficient amount of penetrating oil over the stuck lifters, so they each get coated, and allow the oil to seep into the engine.
Turn off the vehicle and replace the valve covers. Scrap the old gasket off the cylinder head and valve covers, making sure no debris ends up in the valve train. Place the new gasket on each cylinder head, and bolt it snug to the engine.
Take the vehicle out on a drive, bringing it up to highway speed. At higher RPMs, the penetrating oil does its job. After a 20 to 30 minute drive, bring the car back home and listen to it idling. The noisy lifters should be fixed.
